Hydrochloric Acid → 9-Phenyl-9H-carbazole-3-boronic acid

Participants

Reaction Conditions

Reaction Steps

10 g (31 mmol) of 3-bromo-9-phenyl-9H-carbazole was put into a 500 mL three-neck flask, and the air in the flask was replaced with nitrogen. 150 mL of tetrahydrofuran (THF) was put into the flask, and 3-bromo-9-phenyl-9H-carbazole was dissolved therein. This solution was cooled down to −80° C. 20 mL (32 mmol) of n-butyllithium (a 1.58 mol/L hexane solution) was dropped into this solution with a syringe. After dropping, the solution was stirred at the same temperature for one hour. After the stirring, 3.8 mL (34 mmol) of trimethyl borate was added to the solution, and the solution was stirred for about 15 hours while the temperature of the solution was being raised to room temperature. After the stirring, about 150 mL (1.0 mol/L) of diluted hydrochloric acid was added to the solution, and then the solution was stirred for 1 hour. After stirring, an organic layer is separated from the mixture, the aqueous layer was extracted with ethyl acetate, and the extracted solution and the organic layer were combined and washed with saturated sodium bicarbonate. The combined organic layer was dried with magnesium sulfate. After the drying, the mixture was subjected to gravity filtration. The obtained filtrate was condensed to give an oily light brown substance. The obtained oily substance was dried under reduced pressure to give 7.5 g of a light brown solid, which was the object of the synthesis, in a yield of 86%. A synthesis scheme of Step 1 is shown by the following (a-1).

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